Fuse for projectiles



June 21, 1932. 'r- B, DGE 1,863,837

FUSE FOR PROJECTILES Original Filed March 16, 1929 vsir'res PATENTTHOMAS B. DOE, F NEW YORK, N. Y.

j russ ron rnoJEcrILns Application' led March 16, 1929, Serial No.347,491. Renewed November 7, 1931.V

l This invention relates to fuses for projeci tiles ,particularly to thetype of projectile which` isdetonated at a predetermined point in itsflight. Such proj ectiles` are largely emt ployed in antiaircraft` gunlire. lUsually ASuch fuses are operated onthe time principle, theprojectile being detonated at a predetermined time after itis fired. Bymy invention, u on theother hand, I propose to replace the costlyanddelicate timing mechanism now This centrifugal force will overcome theforce employed by a simple device which depends primarily onthe velocityof the projectile and is operated by the pressure of the air on the nose`thereof which, of course, is a function i jectile at any given point inits flight is a function of the distance the projectile from the gun, itis obvious that the air pressure at its forward end at any given pointis also a func l tion of the distance from the gun. lt is, of course,necessary to take into account the height of the projectile, atmosphericcondie tions, etc., but such factors may all be taken into account inthe setting of the fuses. The

air pressure on the nose of thel projectile may be balanced against anysettable yielding means within the projectile, such as spring pressureor the like. prefer to make use of the rotation of the projectile on itsown axis n `(which is imparted by the rifling in the gun) to create theyielding force which opposes the air pressurelby employing free orpartially free masses within theprojectile on which the centrifugalforce acts. l provide a simple A" and` reliable means within theprojectile for "opposing the air pressure means since the speed ofrotation of the projectile is nearly constant quantity, the rotationdecreasing in velocltyvery slowly and at a known rate.

ofthevelocity. Since the velocity of the pro- Y Fig. 2 is a transversesection thereof on line 2-2 of Fig.` 1 looking downwardly.

Fig. 3 is a vertical section of a modified form of fuse in whichcentrifugal force is utilized.

B Fig. 4 is a section taken at right angles to `ig. 3. i f l Fig. 5 is aVertical section of still another modiiication utilizing centrifugalforce.

In the drawing, the forward portion of the projectile only isillustrated as thiscontains all of the firing mechanism. The firing pinor hammer 1 is shown as located within a transverse bore'2 in the noseof the projectile and is normally pressed forwardly by compressionspring 3. When released, the hammer strikes the percussion cap 4andflres the powder train 5 or fuse, leading to the main explosivecharge in the lower part of the projectile. The hammer is normallymaintained locked in the retracted position by one or more detents orlocking pins. One of said pins 6 is a safety catch which prevents allpossibility of the shell being exploded prematurely. Said detent is on amass 7 normally held in place by the split spring ring 8 .which liespartly within a recess 9 in a nut 10 and partly in an annular recess inthe mass 7 When the projectile is discharged from the gun, however, theinertia of said inass 7 is suiiiciently great' to snap it to the bottomof `the bore 11 where it is held by the closure of the ring 9 over thetop thereof. The proj ectile is thus armed and ready to re upon therelease of the main detent or pin 12.

Said pin projects downwardly from a stem 13 having a plurality ofshoulders and threaded portions thereon. vSaid stem at its top is flaredat 14 to form the nose of the projectile and may also be provided with`a slot 15 for rotation by a fusesetter. The stem first passes through alocking ring 16 `threaded in the projectilewhich holds in place arotatably mounted ring or nut 17. j Said ring is threaded interiorly,preferably with a lefthanded thread, and engages corresponding threads18 on the stem. Spring-pressed locking balls 19 (see Fig. 2) are placedin transverse bores in the shell and engage the exterior of said ring17. Said balls serve to lockk the sleeve 17 aga-inst rotation in onedirection, i. e.` clockwise rotation in Fig. 2, but permit the sleeve tobe rotated in the opposite direction. Y

Secured adjacent the bottom of said stem is a fiat coil spring 19. Saidspring is preferably anchored at one end to the stem and at the otherend to a pin 21. The spring is normally under more or less tension, i.Ve., is wound up so that it tends to rotate the stemin va clockwise'direction in Fig. 2. Y By turning the stem by means of a screwdriver orfuse setter in a counterclockwise direction in Fig. 2, the spring willbe Wound up to a greater or less extent. During such operation, however,the nutl?l freely rotates with the stem, so vthat no 4axial adjustmentof the stem takes place.

closures 26. As shown, I prefer lto place' each of said masses in a bore27 which extends transversely but at an angle to a transverse planepassing through the projectile. i The centrifugal force tends toAwithdraw the masses as Ysoon as the Vnormal speed of rotation isapproached, but due to the forward inclination of the bores in whichthey are placed, the centrifugal force is opposed by the inertia ofthemasses While the projectile is receiving itspowerful acceleratingimpulsefrom thepowder. 'l`herefore,` the masses will not be 'disengaged vfromthe locking collar until the shell is well beyond the muzzle of the gun,for it is well known that'the shell continues 'to accelera-te somewhatbeyond the muzzle due tothe following gases. I regard this asV importantbecause during this period the pres# sure on the nose of the projectilemay not have built up sufficiently to hold the same against theunwinding action of the spring.

This form of the invention is set forrange as follows: `The parts'areassembled in the position shown in Fig. l with the detent 12 engagingthe hammer, and the spring under no or slight tension. YThe device isthen set for rangeby turning the nose cap 15. The'centrifugal masses 22do not prevent this since no axial movement of the pin 13 takes placeand thenut 23 has a smooth periphery. vThis adjustment is effected byturning thefstem 13 Counter-clockwise or to the left in Fig. 2s'o thattheV nut' 17 rotates with the stem and no axial movement takes place.After tlie'shell is fired, however,and the lockingfpins are allreleased, the spring will unwind the stem 13 4ing Vdetent 12 is againheld in place by the air pressure on the stem 13 and similar auxiliarylocking masses 22-23 may be provided.

For withdrawing the detent as the air pres-v sure falls below apredetermined amount, I ,have shown a pair of bell crank levers 30-31pivoted at 32-33 on each side of the 4center line of the projectile.A'channel'or runway 841 is shown in each lever in which is placed a ball35 or other free mass. Each ball normally rests in a pocket at thebottom of the levers shown in Fig. 3, but as the'shellrotates the ballsthe actionof centrifugal force will roll the balls up the runways untilthey rest against the adjustablestop-pins '36. pins are shown as havinga portion 37 threaded in a bore 38 in the nose ofthe pro- Vjectile sothat they can beV accurately adjusted for range. The distance rof theball in its outer position from the pivotedV point 'S2-33 Ywilldetermine the lifting force exerted therebyv on the'stem lrsince thelever armis Said altered by such adjustment.V In the form f shown inFig. 3, the runways are also shown as inclined slightly Voutwardly sothat the distance of the ball from thecenterof rotation is alsoincreasedwith the increase in lever arm. i Y

By providing a pair of balls on opposite sides of the shell Iautomatically take care of any out-of-balance that there may be in theshell.- That is, if only asingle ball were provided and the shell didnot rotate about its geometric axis, the force exerted by the ball would'be different from the calculated one because the radius Aof its pathof'rotation would not be the same as its distance from the center lineof theV shell. With my invention, however, if one ball is rotated abouta slightly greater radius than it should, due to defect in the shell,the radius about which the other ball rotates will be correspondinglyreduced so that the upward force exerted on the stem will remain thesame. Y v

It should also be noted that this form of the invention is self-lockingto a certainextent, for, while the shell is leaving the gun, theinertiaiofthe balls during such time will hold Ythemr inthe positionshown in Fig. 3 until the prinierside of thefcenterf of rotation of theshell. i

` l In the form shown in I also make use j gaged by the balls 35, arepivoted respectivewhich the balls bear.

ly at 4041 and are each provided with a projection 42 bearing on acollar 43 on a stern 13". The levers in this case are shown as providedwith downwardly extending and outwardly flaring portions 44-45 againstThe position of said balls along said portions and hence the forceexerted thereby on the levers is adjusted in this instance by mountingthe balls in a cage 46 which is adjusted upwardly or downwardly by meansof upwardly extending arms 47 which are provided with lugs 48 engaging acoarse thread or a spiral groove 49 on the interior of the annular nosepiece 50. Said piece is revolubly mounted near the nose of theprojectile and may be rotated by engaging lugs 50 thereon with aspaniier wrench or the like to set the device for range.

In Fig. 5 I have also shown a somewhat different shape of head 53 on thestem 13". In this instance the head or nose is normally i i spacedslightly from the end, proper, 54 of the projectile so as to leave aspace 55. The nose is stream lined with `respect to the rest of theprojectile so that a negative air pressure exists within the space 55,thereby increasing the effective pressure of the air on the saine. Inaddition, the nose is made more pointed than in the form shown in Fig.1, so that the total air resistance on the shell is less.

From the foregoing, the operation of my invention should be readilyapparent. Due to the safety locks it is impossible to cause a prematureexplosion of the projectile. As, however, the projectile is fired fromthe gun it is armed by the automatic withdrawal of the lock 10 asexplained. Shortly thereafter` asthe acceleration ceases on theprojectile the auxiliary locking devices 22-23 are withdrawn so thattheprojectile is completely armed and the pin 13 or 13 is being pushedoutwardly either by the unwinding spring action in Fig. 1 or by thecentrifugal action `of the balls in Figs. 3 and 5. No firing takesplace, however, as long as the air pressure on the nose of the pin issufcient to over-V come the spring or centrifugal force.

As soon, however, as the point in the path of the projectile is reachedwhere the air pressure falls below a predetermined amount the detent isreleased and the projectile exploded. The accuracy of my fuse depends,of course, somewhat on maintaining the muzzle velocity substantiallyconstant. If the muzzle velocity' is greater than anticipated, the fusewill be set off prematurely with the centrifugal method, as shown inFigs. 3, 4 and 5, be-

` cause the velocity of rotation of the shell will be correspondinglyincreased; while if the muzzle velocity and, therefore, the speed ofrotation, is less than anticipated, the fuse will bet set off too late.On the other hand,

if a spring were employed which wasuniniluenced by centrifugal forces,it would set olf the fuse late where the muzzle velocity was greaterthanl anticipated, and early if the muzzle velocity were less thananticipated.

If these two methods are combined, however,

the error due to change in muzzle velocity may be reduced to averysmallamount. As a matter of fact the form of spring showniin Fig. 1 issubject. to a certain extent, to cenj trifugal action. In other words,centrifugal forces acting on the helical coils tend to spread them andincrease the twisting force `exerted by the spring onthe stem 13,especially if the spring is woundin the proper di- Y recti'on withrespect to the direction of rotation of the shell. This form of theinvention, therefore, really combines the spring and centrifugal methodsand thereby reduces the error referred to.

In accordance with the provisions of the patentstatutes, I have hereindescribed the principle and operation of my invention, together with theapparatus which I now consider to represent the best embodiment thereof,but I desire to have it understood that the apparatus shown is onlyillustrative and that the invention can be carried out by other means.For instance, I employ the term air pressure herein in its broad senseof any pressure (positive or negative) different from atmosphericpressure, which is caused at any part of the projectile by and is afunction of the velocity of flight of the projectile. Also, while it isdesigned to use the various features and elements in the combinationandirelations described, some of these may be altered and others omittedwithout interfering with the more general results outlined, and theinvention extends to such use.

Having described my invention, what I claim and desire to secure byLetters Patent is:

suo

1. In a fuse for projectiles, the combina-A withdrawal of said detent isprevented before the projectile has cleared the muzzle.

2. In a fuse for projectiles, the combination -with the hammer, of adetent for nor-A mally holding said hammerretracted, vmeans subject to'the air pressuredue to the High-t of the projectile for holding saiddetent lin place, andvinovable masses within the projectile subj ecttothe combined centrifugal and acceleration forces created by therotation thereof `and by the acceleration of the projectile forwithdrawing said detent when ,the air pressure becomes a predeterminedmeans .for preventing withdrawaljof saidfdetent until the projectile hasleft the gun.

In testimony whereof I have ya-lixed my si gnature. Y

THOMAS B.` DOE.

amountbut for preventing such withdrawal Y,

until the projectile is beyond the muzzle.

3,. In a fuse for projectiles, the combinai .i

4. In a fuse for projectiles, the combinal tion with the hammer, of adetent for nor mally holding said hammer retracted, yielding meanstending to withdraw said 'detent comprising a lpair of bell crank leverson opposite sides of said detent with one arm of each lever engagingsaid detent and the other arm extending forwardly, a mass movablymounted on each lever, said mass being normally held onthe detent sideof the pivot of each lever by the acceleration of the projectile inleaving the gun but adapted under the action of centrifugal force tomove to theV other side of said pivot when acceleration ceases, wherebya withdrawing force is eX* erted on said detent.

Y 5. In a fuse forprojectiles, the combination with the hammer, of adetent for normally holding said hammer retracted, centrifu-gallyoperated means for withdrawing said detent comprising a lever pivoted toone side of said detent, a mass movably mounted on the lever andadaptedunder the action of centrifugalV force to exert through the lever awithdrawing force on said detent, settable l means for adjusting theposition .of said mass along said lever to vary the range, and means forexerting an opposing force tothe action of said lever and mass.

- 6.' In a fusefor projectiles, the combination with Vthe hammer, of adetent for normally holding said hammer retracted, means subject to theair pressure due to the flight of the projectile for holding said detentin place, movablemasses within the projectile subject to the centrifugalforce created by the rotation y thereof for withdrawing said detent whenthe air pressure becomes a predetermined amount,settable means forvarying the effective force exerted by said masses on Ysaid detent forvarying the range at whichthe shell explodes, and inertiaoperated safetylocking

